India in fear of further attacks after twin bomb blasts kill more than 50

They were still counting the dead early today after a car bomb exploded at Bombay's Gateway of India, among Asia's greatest landmarks and the signature of the country's commercial capital.

The attack ­ one of two large bombs in taxis to detonate in the city yesterday ­ was calculated to cause many casualties, chaos and international headlines by singling out a popular tourist spot.

It did just that.

The number of deaths from both explosions was 52, with more than 150 injured. There were fears that the toll would rise, every new body increasing the communal tensions that plague this divided region.

And there were fears of more attacks: hours after the blasts, nine detonators were found on a railway track leading from the city before a trainload of pilgrims was to pass.

Pakistan moved swiftly to condemn the assaults, which came amid an uncertain thaw in the long-standing enmity between the rival nuclear powers, as "acts of terrorism". Before, Indian leaders have linked Islamabad with terrorist attacks on its soil, including the assault on its parliament in 2001, which caused both sides to mobilise their armies.

Lal Krishna Advani, the Indian Deputy Prime Minister, said similar attacks in Bombay had been launched by the outlawed Students Islamic Movement of India with Lashkar-e-Taiba, based in Pakistan, which is among more than a dozen Islamic groups fighting Indian security forces in Kashmir. There have been eight bombings in as many months in Bombay, but yesterday's stood apart because of the number of victims and the symbolic force of striking a target at the heart of the national consciousness.

Built 80 years ago by British rulers after a visit by George V, the Gateway of India is to Bombay what Trafalgar Square is to London. The giant basalt triumphal arch was an assertion of colonial supremacy but has become the emblem of the nation's trendiest, most confident and most populous metropolis. The place has always been a crowd-puller. Close by stands the five-star Taj Mahal hotel, with a reputation that extends from Bel Air to Sydney's millionaire row. Beyond stretch glorious views of Bombay harbour. Tourists gather in large numbers, and so do vendors, guides, grifters, snake charmers and beggars.

Such was the force of yesterday's Gateway blast that some people were blown off the parapets and into the sea. The two bombs, concealed in taxis, police said, went off within minutes of each other. It was mayhem. The city's phone systems jammed; its hospitals soon filled with shouting, frightened, bleeding people. Police flooded the streets, and security alerts were declared in India's areas of communal tension, including Gujarat, the north-west state that was the scene of last year's massacres, and Delhi, the capital.

The first bomb, about 1pm, detonated in south Bombay's Zaveri Bazaar, close to a Hindu temple and within a popular market crammed with gold and jewellery stalls. The shops are largely Hindu-owned, but Muslim craftsmen also work there. "There were hands and legs flying in the air, and blood everywhere," said Anil Punjabi, a jewellery shop owner.

Dr S Manoj, at Bombay's JJ Hospital, said: "I have never seen anything so horrible. It was just body parts ... some with no faces at all. The bodies were all burnt."

He said some injured were being treated for broken bones after being trampled in stampedes after the explosions.

By nightfall, no one had claimed responsibility for the attacks, the worst in Bombay since more than 250 people were killed in 1993 in a bombing blitz directed at hotels and businesses, attacks seen then as retaliation by the Muslim minority after a wave of communal violence.

Jack Straw, the Foreign Secretary, condemned the bombing which, he said, underscored the need to deal with "the poison of international terrorism". The Foreign Office said there is no reason to believe that hotels or foreign nationals were a target.

But there were plenty of theories in India yesterday, focusing on Muslim extremists. "There are many jehadi groups out, let loose by the enemy country," one senior police official, Ranjit Sharma, said, in a reference to Pakistan.

Significantly, the bombings coincided with the release of the results of an archaeological investigation into one of the nation's most combustible issues, the disputed religious site at Ayodhya. In 1992, Hindu fanatics tore down a 16th-century mosque in the north Indian city, claiming it stood on the site of an ancient temple marking the God Rama's birthplace, which they want rebuilt.

Thousands died in the communal bloodletting that followed, the most severe since India's independence in 1947. It became a cause célèbre for Hindu extremist movements, and their allies in the Bharatiya Janata Party, which leads India's governing coalition. The report, by the Archaeological Survey of India, said that below the mosque's ruins it found evidence of a "massive structure", including pillar bases and lotus motifs common to north Indian temples. It did not state categorically that the remains were Hindu, but the findings still seem certain to cause much controversy.

Communal relations remain under great strain. There have long been fears of a backlash to the slaughter of hundreds of Muslims in Gujarat last year. This, too, could be traced to Ayodhya: the violence erupted after a Muslim attack that killed dozens of Hindu activists on a train returning from the city. It may be that yesterday's events were another vengeful turn in the spiral.

Nor are matters helped by Gujarat's demagogic chief minister. The Muslim-bashing Nahrendra Modi is about to embark on a three-day odyssey through his state, parading the ashes of an Indian nationalist who died in 1930, but whose remains he has recovered from Switzerland. Emotions will be at boiling point.